1. Field of the Invention
This invention relates to a foamed polyurethane-forming composition, a foamed polyurethane and a process making the same. More particularly, it relates to a composition and process capable of providing a foamed polyurethane substantially free from non-uniform density distribution and suitable for model materials, and such a formed polyurethane.
2. Description of the Prior Art
There have been proposed techniques for producing rigid polyurethane foams of reduced non-uniform density distribution, with use of microballoons and blowing agents.
Rigid polyurethane foams thus prepared, however, have non-uniform density distribution remained undiminished, and it is inevitable to cause warpage after processing for producing model materials.